As is known, magnetic switch sensors are used to detect proximity of a target to one or more magnetic field sensing elements of the sensor, which target and sensor are capable of motion relative to one another. Example devices may include a stationary portion to which the sensor is attached and a movable portion including a magnet, such as cellular telephones and laptop computers having magnets in moveable door or cover portions.
Some magnetic switch sensors are capable of detecting proximity of a magnetic target regardless of the orientation of the magnetic poles of the magnet relative to the sensor, a capability sometimes referred to as “omnipolar” operation. One such sensor is described in a U.S. Pat. No. 7,307,824, entitled “Magnetic Pole Insensitive Switch Circuit”, which patent issued on Dec. 11, 2007 and is assigned to the Assignee of the subject application.